Two gateways on same network
I'm setting up a Debian antispam mail relay. I have two gateways on the
network (two separate internet connections):
4mbit ADSL = 192.168.1.6
128k line = 192.168.1.1
Both have NAT firewalls, both forward port 25 to the Debian box. I'm
trying to do the following:
Always use 192.168.1.6 as the default gateway, except when:
1. Connections are received via 192.168.1.1. Because if it doesn't
reply via the same gateway, the connection just times out.
2. 192.168.1.6's connection goes down, for whatever reason.
So basically the leased line would be a backup MX.
I have put two network cards in, both with IPs on the same network, but
with different gateways specified in /etc/network/interfaces. But for
some reason both try to use 192.168.1.1 as the gateway, regardless.
If the second network card is not necessary, that would be OK too.